1. Field of the Invention
This invention relates to the art of tubular speakers for use in a stereo system for radiating acoustic output throughout a wide angle in generally horizontal planes so as to provide maximum sound in a minimum floor space.
2. Description of the Prior Art
The Gellman U.S. Pat. No. 2,896,737 describes an extension loudspeaker for radio, television receivers, phonographs, and the like. It has a tubular casing supporting a conventional cone-type speaker mounted intermediate the length thereof. This speaker is either mounted horizontally on a supporting surface, or it may be mounted vertically on a vertical wall surface. Apparently, the main invention of this patent is the adjustability of the support legs.
The Virva et al. U.S. Pat. No. 3,443,660 describes a mid-range speaker and enclosure combination which comprises a cardboard cylindrical enclosure supporting a soft cone, mid-range loudspeaker mounted in one end thereof. The speaker has a rigid frame with a drum portion at the rear, and the cylindrical enclosure is frictionally secured to the loudspeaker by forcing it over the drum portion to form a substantially airtight seal. The length of this cylindrical enclosure is approximately equal to one-fourth the wave length of the natural resonant frequency of the loudspeaker, thereby providing a substantially tuned enclosure.
The Robinson U.S. Pat. No. 3,945,461 describes a sound speaker system having an elongated vertical cylinder that is open at both ends. A secondary cylinder is telescopically fitted with the lower end of the cylinder. The lower end of the secondary cylinder is mounted on a flat, horizontal, annular surface which is supported on vertical legs from the floor. The speaker is mounted in the central opening of the annular member facing downwardly. There are three adjustable stop means for positioning the upper cylinder with respect to the lower, secondary cylinder. This loudspeaker system is designed to be placed in the corner of a room so that sound emanating from the lower and upper ends is reflected by the floor and ceiling corners respectively into the room.
The Siebert U.S. Pat. No. 3,978,941 describes a cylindrical speaker enclosure for providing an acoustically balanced output with improved audio quality at low level reproduction. The speaker is mounted intermediate the ends of the tubular speaker. The inner walls of the tubular shelf are covered with an acoustically absorbent material. At the bottom end of the cylindrical shell is an annular plate which serves as an elastic diaphragm forming a closure across the bottom end of the shell chamber. There is a venting tube vertically disposed over the central opening in this annular plate which allows for the transfer of air from the inside of the chamber to the outer atmosphere. This speaker enclosure is mounted above a surface so that the elastic diagragm on the bottom is not directly contacting a supporting surface.
The Berlant U.S. Pat. No. 4,348,549 describes a loudspeaker system for radiating acoustic output throughout 360 degrees, in generally horizontal planes, comprising a tubular enclosure having a polygonal cross section (rectangular). There is an upper tweeter assembly mounted in the upper end of the rectangular enclosure, and a lower woofer assembly, including a speaker with a conical diaphragm mounted at the lower base of this enclosure. A down-turned conical member is positioned at the top of the speaker, above the tweeter, for changing the direction of the radiated acoustic energy in the horn by an angle of approximately 90 degrees.
The Australian Pat. No. 143,597 describes a loudspeaker unit having a hollow column formed by a semi-circular arcuate member of plywood forming about 240 degrees of a circle, and a somewhat curved panel of plywood closing the gap. A series of radially-spaced vertical feet support this column, and a conventional cone loudspeaker is mounted on a baffle at the top of the column. A lining of sound-absorbing material is fitted on the interior of the column for reflecting sound waves from the speaker in a substantially horizontal direction.